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Millimeters to fractional inches

Convert millimeters to the nearest 1/16, 1/32 or 1/64 inch, like the marks on a tape measure, with the math shown step by step.

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Inches (fraction)
1 3/16 in

30.58 mm ≈ 1 3/16 in

Exact size 1.204 in · 1 3/16 in is 0.42 mm under

Also equals

How it works

in = mm ÷ 25.4

One inch is exactly 25.4 millimeters, so dividing by 25.4 gives inches as a decimal. To read that on a tape measure, count how many 1/16-inch marks it covers, round to the nearest mark, then simplify the fraction.

  1. Divide by 25.4 to get inches 30.58 ÷ 25.4 = 1.2039 in
  2. Count the 1/16 in marks 1.2039 × 16 = 19.26 → nearest mark: 19
  3. Simplify the fraction 19/16 in = 1 3/16 in
Picture it

30.58 mm is 1.204 in, between marks. The nearest mark is 1 3/16 in (0.42 mm under).

Nearest mark Exact size

Nearby values

Millimeters Inches (fraction) Exact Centimeters
27.58 mm 1 1/16 in 1.09 2.76
28.58 mm 1 1/8 in 1.13 2.86
29.58 mm 1 3/16 in 1.16 2.96
30.58 mm 1 3/16 in 1.2 3.06
31.58 mm 1 1/4 in 1.24 3.16
32.58 mm 1 5/16 in 1.28 3.26
33.58 mm 1 5/16 in 1.32 3.36

Printed from rocketcalc.io/length/mm-to-inch-fractions/30.58